. The objectives of the proposed research will be two-fold (1) obtain data on the ability of ODT as a means of diagnosis of human skin cancer, as compared to conventional histologic examination; and (2) monitor intratumoral blood flow in real-time during Photodynamic Therapy (PDT). The administration of a sufficient dose of light, at the appropriate wavelength, to photosensitizer-containing tissue is essential for PDT. Accordingly, monitoring the effects of light delivery in tissue during PDT has great clinical significance.